Grandma (3)
I believe the answer is:
nan
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">grandma</span>' is the definition.<br/ ><span class="explanation-format__explanation">(nan can informally mean a grandmother)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for nan that I've seen before include "Darling dog" , "type of slightly leavened bread" , "Ancestor" , "Granny; bread" , "Grandmother (colloq.)" .)